As a modern society recently enters a ubiquitous age allowing information exchange anywhere and anytime, a Personal Area Network (PAN) via which an individual collects various data from neighboring mobile terminals and processes them has emerged. Under this circumstance, the number of personal area terminals directly carried by individuals or found in the neighborhood, that is, the number of mobile terminals, also gradually increases. Accordingly, information exchange between the mobile terminals becomes active.
To exchange data between the mobile terminals, a communication method for connecting the mobile terminals with each other is required. As a traditional connection method, a communication method using a wired line exists, but this method has a disadvantage of entangled lines and causing much inconvenience when a user carries a cable. Therefore, for access between personal area terminals, (that is, mobile terminals) various wireless communication schemes such as Bluetooth, IrDA, ZigBee, Ultra Mobile Broadband (UMB), and the like, have been commercialized or are under development.
Recently, a technique for transmitting/receiving data using a human body as a medium of electrical signal transfer has been suggested. An apparatus for transmitting/receiving an electrical signal using a human body as a medium is applied in various fields including medical diagnosis equipment. An apparatus for transmitting data using a human body as a medium of electrical signal transfer, or receiving and processing data transmitted by the medium of a human body includes an electrode for directly contacting a human body or contacting a human body with a coating interposed, and a human body communication module for transmitting/receiving an electrical signal by the medium of a human body via this electrode. Since the apparatus for transmitting/receiving an electrical signal by the medium of a human body can transfer an electrical signal by only bringing a human body into contact with a specific device, the apparatus can transmit data required between a user and a system even without a separate wired line or wireless communication equipment. User convenience in data transmission can be improved even without establishing separate wired/wireless communication equipment or a separate communication line by applying such a human body communication apparatus to various fields.
To reduce power consumption during a stand-by state before contact with a human body, the above-described human body communication apparatus inserts a human body contact detector to minimize power consumption of a micro controller and a transmission/reception circuit until the contact is made.
However, in the case where only the contact detector is provided, a problem that, due to a human body antenna effect, a communication process is performed by only detection of a human body contact, even under a circumstance where wireless communication via air is possible but communication using a human body cannot be performed occurs. For example, even in the case where only one of a transmitter and a receiver is brought into contact, or even in the case where a human body communication apparatus exists in a pocket, or even in the case where a contact is not made between users who own or carry human body communication apparatuses in pockets, contact detection is made but wireless communication is performed instead of human body communication.
More particularly, even in the case where a high frequency band is used to achieve high speed transmission, a human body antenna effect becomes serious and such a problem becomes serious even more.